Guo Hui-jie, Yue Lin
Department of Stomatology, Peking University People's Hospital, Beijing 100044, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2009 Dec 18;41(6):699-701.
To establish an in vitro root canal model infected by Enterococcus faecalis and to observe the morphology, distribution and relative position of Enterococcus faecalis in infected root canals.
Ten human healthy premolars extracted for orthodontic reasons were collected. Following sterilization, a total of 5 specimens were aseptically transferred to separate Eppendorf tubes containing 1.5 mL brain-heart infusion broth (BHI) inoculated with 0.1 mL Enterococcus faecalis suspension that had been adjusted to Mcfarland 5, and were incubated at 37 degrees Celsius for 21 days. The other 5 specimens were as controls. The roots of all specimens were then split into two halves along the mesiodistal axis. One half was processed with light microscopic (Brown & Brenn stain) to check the bacteria in dentinal tubules, and the other was observed with SEM to investigate the bacterial status in infected root canals.
Enterococcus faecalis could penetrate into the dentinal tubules about 330-1 000 mum. A dense bacterial aggregation composed of Enterococcus faecalis and amorphous matrix was observed in the apical third of the root canals, whereas Enterococcus faecalis were seen free-floating or planktonic in the crown and middle third of the root canals . No microorganisms were found in the root canals of the controls.
Enterococcus faecalis could form bacterial biofilm on the root canal walls and penetrate into the dentinal tubules. The in vitro model designed was simple, and had good practicability to make a further comparative evaluation of various antimicrobial methods in the reduction of intracanal bacteria.
建立粪肠球菌感染的体外根管模型，观察粪肠球菌在感染根管内的形态、分布及相对位置。
收集因正畸原因拔除的10颗健康人前磨牙。消毒后，将5个标本无菌转移至单独的含有1.5 mL脑心浸液肉汤（BHI）的Eppendorf管中，该肉汤接种了0.1 mL已调至麦氏比浊度5的粪肠球菌悬液，并在37摄氏度下孵育21天。另外5个标本作为对照。然后将所有标本的牙根沿近远中轴劈成两半。一半用光学显微镜（布朗和布伦染色）处理以检查牙本质小管中的细菌，另一半用扫描电子显微镜观察以研究感染根管内的细菌状况。
粪肠球菌可侵入约330 - 1000μm的牙本质小管。在根管根尖三分之一处观察到由粪肠球菌和无定形基质组成的致密细菌聚集体，而在根管冠部和中部三分之一处可见粪肠球菌自由漂浮或呈浮游状态。对照组根管内未发现微生物。
粪肠球菌可在根管壁上形成细菌生物膜并侵入牙本质小管。所设计的体外模型简单，在对各种抗菌方法减少根管内细菌的效果进行进一步比较评估方面具有良好的实用性。
